New autofill save & update password prompt pixels for alignment with iOS

[amddg44]

Task/Issue URL: https://app.asana.com/0/72649045549333/1207361449520263/f
Tech Design URL:
CC:

Description:
New pixels to bring macOS password management pixel reporting up to date with iOS

Steps to test this PR:

Using DuckDuckGo as your Password Manager:

Save Login

1. Visit https://fill.dev/form/login-simple and enter new credentials (both username and password) and click Login
2. Confirm the pixel m_mac_autofill_logins_save_login_inline_displayed fires when the Save prompt appears
3. Click Don't Save and confirm the pixel m_mac_autofill_logins_save_login_inline_dismissed is fired
4. Repeat Step 1, but this time click Save and confirm the pixel m_mac_autofill_logins_save_login_inline_confirmed is fired

Update Password

1. Go back to https://fill.dev/form/login-simple and choose the credentials saved as part of Save Login but modify the password and click Login
2. Confirm the pixel m_mac_autofill_logins_update_password_inline_displayed fires when the prompt appears
3. Click Don't Update
4. Confirm the pixel m_mac_autofill_logins_update_password_inline_dismissed fires
5. Repeat Step 1
6. Click Update and confirm that the pixel m_mac_autofill_logins_update_password_inline_confirmed fires
7. Repeat Step 1 but this time also modify the username in the prompt
8. Click Update and confirm that both pixels m_mac_autofill_logins_update_username_inline_confirmed and m_mac_autofill_logins_update_password_inline_confirmed are fired (since both were modified)

Save Password

1. Visit https://news.ycombinator.com/login and enter a (min 4 char) password (no username) and click login
2. Confirm the pixel m_mac_autofill_logins_save_password_inline_displayed fires when the Save prompt appears
3. Click Don't Save and confirm the pixel m_mac_autofill_logins_save_password_inline_dismissed is fired
4. Repeat Step 1, but this time click Save and confirm the pixel m_mac_autofill_logins_save_password_inline_confirmed is fired

Update Username

1. On https://news.ycombinator.com/login enter a username and using the previously saved password click login
2. Confirm the pixel m_mac_autofill_logins_update_username_inline_displayed fires when the prompt appears
3. Click Don't Update and confirm the pixel m_mac_autofill_logins_update_username_inline_dismissed fires
4. Repeat Step 1 but this time click Update and confirm the pixel m_mac_autofill_logins_update_username_inline_confirmed fires

Bitwarden

1. Update your password manager to be Bitwarden and repeat the steps from sections Save Login and Save Password confirming the same pixels fire

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Internal references:

Pull Request Review Checklist
Software Engineering Expectations
Technical Design Template
Pull Request Documentation

[SabrinaTardio]

Works as expected! LGTM
I left 2 small comments